This invention relates to a key duplicating machine and more particularly to such a machine that utilizes a grinding wheel to shape a key blank in accordance with an existing key.
The key duplicating machines of the prior art provide for punching a key blank to duplicate an existing key either by measurement of the notches of the existing key or by following a coding thereof as provided for the key. With such an approach, it is necessary to advance the key blank step-by-step past the punching station for successively forming notches of selected depth. It should be evident that such machines not only take time to operate but require expensive machining of the parts to provide for accuracy in the forming of notches of the proper shape and depth on the key blank.
According to the present invention, a key duplicating machine makes use of a rotating grinding wheel having a cutting edge. A reference edge on a fixed guide member is spaced from the cutting edge of the grinding wheel. A shaft having an axis extending parallel to the axis of rotation of the grinding wheel is disposed between the grinding wheel and the guide member. The shaft is supported in linear bearings such that it can be both rocked about and moved along the axis thereof. A Y-shaped keyholder provides two angular arms with the existing key to be duplicated held on one and the key blank held on the other. The keyholder is attached to the shaft and disposed with the existing key biased to bear against the reference edge of the guide member and with the key blank adjacent the cutting edge of the grinding wheel. Thus, as the existing key on the one arm of the keyholder is moved lengthwise past the guide member by moving the shaft along its axis, the keyholder is rocked about the shaft axis and causes the key blank on the other arm thereof to be moved laterally into the cutting edge of the grinding wheel to form the notches therealong. A projection is provided on the keyholder which cooperates with a linear cam to facilitate the loading and unloading of the key blank thereon. Thus, when the keyholder is moved along the shaft axis away from the vicinity of the grinding wheel, the projection provides for rocking the keyholder away from the cutting edge thereof.
Accordingly, one of the objects of the present invention is to provide an inexpensive key duplicating machine that utilizes a grinding wheel to cut notches on the key blank in accordance with notches on an existing key.
Another object of the present invention is to provide a key duplicating machine that duplicates the notches of an existing key on a key blank with a single swing of an operating arm.
Another object of the present invention is to provide a key duplicating machine that automatically rocks the holder for a key blank away from the vicinity of the cutting edge of the grinding wheel when the holder is moved into its normal rest position.
With these and other objects and advantages in view, the invention consists of the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are obtained as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.